Polarimetry and astrometry of NIR flares as event horizon scale, dynamical 
probes for the mass of Sgr A*

Abuter, R.; Aimar, N.; Amaro-Seoane, P.; Amorim, A.; Bauböck, M.; Berger, J. P.; Bonnet, H.; Bourdarot, G.; Brandner, W.; Cardoso, V.; Clénet, Y.; Davies, R.; de Zeeuw, P. T.; Dexter, J.; Drescher, A.; Eckart, A.; Eisenhauer, F.; Feuchtgruber, H.; Finger, G.; Förster Schreiber, N. M.; Foschi, A.; Garcia, P.; Gao, F.; Gelles, Z.; Gendron, E.; Genzel, R.; Gillessen, S.; Hartl, M.; Haubois, X.; Haussmann, F.; Heißel, G.; Henning, T.; Hippler, S.; Horrobin, M.; Jochum, L.; Jocou, L.; Kaufer, A.; Kervella, P.; Lacour, S.; Lapeyrère, V.; Le Bouquin, J.-B.; Léna, P.; Lutz, D.; Mang, F.; More, N.; Ott, T.; Paumard, T.; Perraut, K.; Perrin, G.; Pfuhl, O.; Rabien, S.; Ribeiro, D. C.; Sadun Bordoni, M.; Scheithauer, S.; Shangguan, J.; Shimizu, T.; Stadler, J.; Straub, O.; Straubmeier, C.; Sturm, E.; Tacconi, L. J.; Vincent, F.; Fellenberg, S. von; Widmann, F.; Wielgus, M.; Wieprecht, E.; Wiezorrek, E.; Woillez, J.

doi:10.1051/0004-6361/202347416

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Polarimetry and astrometry of NIR flares as event horizon scale, dynamical probes for the mass of Sgr A*

MPS-Authors

/persons/resource/persons284702

Amaro-Seoane, P.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons268015

Bourdarot, G.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons208361

Davies, R.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons146381

Dexter, J.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4766

Eisenhauer, F.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons16286

Feuchtgruber, H.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons286009

Finger, G.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4923

Förster Schreiber, N. M.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons214427

Gao, F.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4590

Genzel, R.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4768

Gillessen, S.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons138161

Hartl, M.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons79044

Haussmann, F.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4584

Lutz, D.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons269976

Mang, F.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons286011

More, N.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons16190

Ott, T.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4782

Pfuhl, O.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4786

Rabien, S.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons294467

Ribeiro, D. C.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons288738

Sadun Bordoni, M.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons232571

Shangguan, J.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons206401

Shimizu, T.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons248280

Stadler, J.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons232635

Straub, O.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4650

Sturm, E.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons4582

Tacconi, L. J.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons206120

Fellenberg, S. von
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons214431

Widmann, F.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons16329

Wieprecht, E.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

/persons/resource/persons16335

Wiezorrek, E.
Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;

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Citation

Abuter, R., Aimar, N., Amaro-Seoane, P., Amorim, A., Bauböck, M., Berger, J. P., et al. (2023). Polarimetry and astrometry of NIR flares as event horizon scale, dynamical probes for the mass of Sgr A*. Astronomy and Astrophysics, 677: L10. doi:10.1051/0004-6361/202347416.

Cite as: https://hdl.handle.net/21.11116/0000-000E-A311-6

Abstract

We present new astrometric and polarimetric observations of flares from Sgr A* obtained with GRAVITY, the near-infrared interferometer at ESO’s Very Large Telescope Interferometer (VLTI), bringing the total sample of well-covered astrometric flares to four and polarimetric flares to six. Of all flares, two are well covered in both domains. All astrometric flares show clockwise motion in the plane of the sky with a period of around an hour, and the polarization vector rotates by one full loop in the same time. Given the apparent similarities of the flares, we present a common fit, taking into account the absence of strong Doppler boosting peaks in the light curves and the EHT-measured geometry. Our results are consistent with and significantly strengthen our model from 2018. First, we find that the combination of polarization period and measured flare radius of around nine gravitational radii (9R_g ≈ 1.5R_ISCO, innermost stable circular orbit) is consistent with Keplerian orbital motion of hot spots in the innermost accretion zone. The mass inside the flares’ radius is consistent with the 4.297 × 10⁶ M_⊙ measured from stellar orbits at several thousand R_g. This finding and the diameter of the millimeter shadow of Sgr A* thus support a single black hole model. Second, the magnetic field configuration is predominantly poloidal (vertical), and the flares’ orbital plane has a moderate inclination with respect to the plane of the sky, as shown by the non-detection of Doppler-boosting and the fact that we observe one polarization loop per astrometric loop. Finally, both the position angle on the sky and the required magnetic field strength suggest that the accretion flow is fueled and controlled by the winds of the massive young stars of the clockwise stellar disk 1–5″ from Sgr A*, in agreement with recent simulations.